Sound transmitting means for aircraft sonic altimeters



25, 1942. H. REHM ETAL SOUND TRANSMITTING MEANS FOR AIRCRAFT SONIC ALTIMETERS Filed May 28, 1938 2 Sheets-Sheet 1 Zla ' INVENTOR5.

BY ATTORNEY.

M 25, 1942. H. REHM ETAL SOUND TRANSMITTING MEANS FOR AIRCRAFT SONIC ALTIMETERS Filed May 28, 1938 2 Sheets-Sheet 2 66?: 43 lmsv T,

62 4o IN VENTO 5 fuwh M TTORNEY.

Patented Aug. 25, 1942 SOUND TRANSMITTIN CRAFT SONIC G MEANS FOR AIR- ALTIMETERS Helmut Rehm and Hans Schuchmann, Berlin- Charlottenburg,

Germany, assignors to Siemens Apparate und Maschinen Gesellschaft mit beschrankter Haftung, Berlin, Germany, r corporation of Germany Application May 28, 1938, Serial No. 210,800

7 Claims.

This invention relates to sound transmitting means, and more particularly to means adapted for use in association with aircraft sonic altimeters, for transmitting a sound impulse and governing the duration thereof.'

In measuring the duration of sound impulses in sonic altimeter arrangements, consideration must be given to the time interval which is to be measured, i. e., the interval between transmission and reception of a sound impulse. The shorter this interval is, the shorter must be the duration of the sound impulse. If particularly low altitudes are to -be measured, as is the case Germany December 21, 1934 when the aircraft is landing, the duration of the sound impulses must be proportionately short. If the same sonic altimeter arrangement is used for measuring both very short and very long time intervals, i. e., both low and high altitudes, it is advantageous that the duration of signal or sound impulse'be adjustable. 1

Signal transmitting arrangements heretofore proposed of this character have failed to provide means for adjusting the duration of the signal or have been too complicated in construction. One of the objects of the present invention is to provide novel means of the above character.

wherein a sound impulse of adjustable duration may be produced.

An additional object of the invention is to provide novel means of the above character whereby sound impulses may be produced which are of such duration that at do not overlap. e

A further object is to provide novel sound impulse governing means which are simple in construction.

Another object is to provide novel signal imlow altitudes they pulse governing meansfor use with sonic altimeters which means enable accurate altitude measurement at both high and low altitudes.

The above and further objects and novel features will more fully appear from the following detailed description when the same is read in connection with the accompanying drawings. It

is to be expressly understood, however, that thedrawings are for purposes of illustration only and are not intended as a definition of the limits of the invention, reference for this latter purpose being had to the appended claims.

In the drawings, wherein like reference characters refer to like parts throughout the several Views,

Fig. 1 is a side elevation, partly in section, of one embodiment of the present invention;

-Fig. 2 is aside elevation, partly in section, of

means which may be employed in the first em-' bodiment for closing. the valve of the device;

Fig. 3 is a side elevation, partly in section, of another form of means which may beemployed in the first embodiment for closing the valve of the device;

Fig. 4 is a sectional view taken on line IVIV of Fig. 5 showing a secondembodiment of the invention;

Fig. 5 is a sectional view taken in line V-V of Fig. 4;

.Fig. 6 is a view of the several. moving elements shown in Fig. 5 in an operating position; and,

. Fig. 7 is a view of the parts shown in Fig. ,6 in a second operating position.

The form of the invention illustrated in the accompanying drawings by way of example is a device adapted for use with sonic altimeters for aircraft whereby a sound impulse of adjustable duration may be produced. The apparatus comprises sounding means such as a whistle which is sounded by a fluid pressure medium which, in turn, is governed by a suitable spring loaded valve. Means are provided for lifting the valve,

' which is in communication, by means of a 'con- Fig. 1a; is a trigger releasing arrangement 55 duit II, with a suitable vessel (not shown) containing a fluid medium. under pressure or with any source of fluid under pressure. A valve I3 is located in the conduit II, the valve having shafts l3a and lab extending from the upper and lower 'faces thereof, respectively. A coil spring l4 surrounding shaft l3a normally holdsvalve IS in the closed position. Valve shaft lib'extends through a bore, having'suitable packing (not shown) in conduit ll. Theiree end of said shaft which protrudes from said bore is sit- Y uated opposite-a hammer I which is mounted upon a hammer lever I! having arms I51; and l5b. Lever l5is pivotally mounted at IG where said arms are joined. A form of energy storing means, 'for example, a ,draw spring i1, is at- 'lever to the cocked position and arms I80 and |8b and pivotally mounted at I! whereby the hammer lever I is maintained in cocked position. Arm |8b constitutes an armature for an electromagnet 2|! which may be energized by connection to a suitable energy source (not shown) whereby arm |5a is released and the hammer lever |5 moves away from its cocked position.

Means are provided for returning the hammer thus charging the energy storing means, comprising (Fig. 1) a piston arrangement actuated by the pressure agent which flows when the valve I3 is open. The arrangement comprises a cylinder 2| which may be formed integrally with conduit I. A piston 22 having a rod 23 is movable within cylinder 2| and is normally held adjacent one extremity thereof by a spring 24; the rod 23, however, extends from said cylinder through a suitable central bore in one extremity thereof. The cylinder 2| at a point above piston with conduit II at a point below valve l3, i. e., between the valve l3 and the whistle II), by means of a conduit 25.

In order that the duration of the sound impulses may be controlled, means are provided for regulating the period during which valve I3 remains open comprising means for adjusting the flow of pressure medium in conduit 25 to the arrangement for returning lever I! to the cooked position. The means are constituted, in the form shown, by a needle valve 260. which controls the sizeof the orifice at the mouth of conduit 26..

26a may be moved by suitable manually operable means (not shown).

In operation. the electromagnet 20 is momentarily energized. armature |8b is attracted which displaces the trigger l8a. Lever I5 is released and immediately drawn by spring H in a counter-clockwise direction, whereby the hammer portion M at the extremity of arm--|6b strikes The needle valve the valve rod lib opening valve l3 against the pressure of spring II. a The pressure medium, therefore. passes the valve and sounds whistle- III. A small quantity of the pressure medium,

however, passes through conduit 25 and forces" piston 22 downwards against the pressure of spring 24 whereby piston rod 22 engages lever arm |5b and forces the same in a clockwise 'directlon against the pressure of draw spring II to the cooked position of hammer lever IS. The valve I2 is forced towards its seat by the action of spring I. When seated, the valve is held by the combined pressures of said spring andthe pressure medium. The period which is required to reseat the valve I2 after it has been opened is a function of the flow of pressure mediumto cylinder 2|, which flow is regulated by needle valve 26a In the arrangement for returning lever l5 to its initial position shown in Fig. l, the motion of the piston 22' is substantially uniform. Consequently, .there is a corresponding closing motion of valve l3. It may be desired that the closing motion of valve l2 occur slowly at first and then rapidly. Return means are provided for accomplishing this, as shown in Figs. 2 and 3, each of which may replace the return means shown in 22 is in communication beof such length that it .45. becomes rapid and hammer lever I6 Fig. 1. The remaining parts of this embodiment remain unchanged.

In Fig. 2, a cylinder 2|a has two concentric bores of different cross-sectional areas, the upper bore having the smaller area of the two. A double piston member comprising pistons 26 and 21 which are rigidly interconnected by a central rod 28, fit into the smaller and larger bores, re-

spectively. Attached to piston 21 is a main rod 29 which extends through a central bore in an end plate of said cylinder. A coil spring 3|! surrounds main rod 29 and yieldingly urges the two pistons in the direction of the arrow. In order to prevent a vacuum from forming above piston 26 when the arrangement is moved against the pressure of spring 30, a small air vent 3| is provided in an upper end plate adjacent piston 26. The 7 cylinder is in communication withconduit H by means of the channel 25 which entersthe cylinder between pistons 26 and 21.

In operation, when a pressure agent enters the cylinder, it tends to force the piston 26 in one direction and the piston 21 in an opposite direction. Since the latter piston has the greater area of the two, the double pistons move slowly downwardly against spring 30 in response to the difference in the forces acting thereon. As soon. however, as piston 26 moves into the larger of the two bores, the effective pressure is no longer a function of the differenceof the forces acting on said pistons but is equal to the actual pressure of the agent in the cylinder. Consequently,

the double pistons move rapidly against the pressure of spring 30. s

The length of the piston rod 29 can be chosen, if desired, so that its free extremity does not contact the lever |5b until after piston 26 has moved into the larger bore, but the free extremity may also contacts said lever immediately after valve I3 is opened. If the free extremity of rod 29 engages lever lib immediately after valve I3 is opened, said valve closes with a motion which at first is slow, but when small piston 26 energes from its small bore. the motion is quickly moved into the cooked position.

In order to obtain a refined adjustment of the small piston 26 remains to provide added means in its small bore, and for controlling the duration of sound impulses. the conduit 26 as illus- 1 and 26b (Fig. 3).

trated in Fig. 3, is divided into two branches 26a, The former branch enters the cylinder 2la between pistons-26 and 21; the latter branch enters the cylinder above piston 26, i. e.,.between the cylinder head and said piston. In conduit 25b a throttle valve 22 is provided for regulating the flow of the pressure agent. The return arrangement shown in Fig. 3 'with the exception of the above-described throttle valve attachment is similar to that shown in Fig. 2.

The operation of the return means illustrated in Fig. 3 is similar to that of the means shown in Fig. 2, with the exception that by adjustment of valve 32 it is possible to govern the proportion of the pressures acting upon the two faces of piston 26, and thereby to govern the total force acting on the two pistons and hence the speed thereof. The speed control by valve 22, however, is effective only while piston 26 is within the smaller bore.

If, in the first embodiment; the electromagnq; 2|! is still excited after the return of lever I! to the position shown, then the series of events is repeated, 1. e., the opening andclosing of valve 2,204,200 I 3 reoccurs. It is, therefore, possible that a plu-' rality of sound impulses may be produced in rapid succession. In order to prevent this, the period 01' excitation of the electromagnet must be as short as possible. However, it is not always possible to excite the magnet for a suillciently short period. Consequently, there is provided for association with magnet 23 a second electromagnet 3.3 (Fig. 1a) which maybe connected in series or in parallel therewith. The action of the second magnet may be, for a purpose to appear later, retarded by suitable means for a fraction of a second. An armature 34 is provided, which is normally withdrawn from said second electromagnet by a spring 36 so that upon simultaneous energization of both magnets 23 and 33, armature I3 is moved first and armature 34 momentarily thereafter since the latter armature movement is retarded somewhat .by spring 35. Armature 33 pivots coaxially with armature l3 and positions a secondtrlgger portion 36 which is adjacent trigger 13d. and is attached to member 34 by a rod 31. Portion 36 does not engage lever I611 when the electromagnets are deenergized.

In the operation of the double trigger arrangement, the electromagnets are connected to a suitable energy source. Magnet 23 attracts armature l3, thus releasing lever i5. The attrac- I tion of magnet 33 is retarded a suiilcient length of time to permit the release of-said lever. If the magnets are still energized when lever it returns to its initial position, trigger l3 will not engage said lever but trigger 36 which in the meantime has moved into an obstructing position, will do so. If the two electromagnets are deenergized thereafter, trigger I3 will move into the obstructing position and the second trigger 36 will be disengaged by spring 33.

In the embodiment .shown in Figs. 4 to 7, a third novel form of the apparatus is provided.

'A lever 33 of this embodiment corresponds to lever i3 of Fig. 1. Lever 33- is pivotally mounted at 33 and yieldingly urged in acounter-clockwise direction by aspring 33. Intermediate the extremities of said lever is a weighted lug 3| which is positioned so as to strikea valve rod 32 of a valve 33 which controls the flow of a pressure agent from a container 33. Valve 33 is resiliently urged towards the closed position by a spring (not shown). A conduit 45 is provided on the exhaust side of .valve 43 which leads into a cylinder 33 having a removable inner sleeve portion 41 in which moves a piston43 having a rod 33, the piston being yieldingly urged toward a cylinder head 33 by a spring 6|. Rod 43 extends through a suitable end plate and is adapted for "striking a1ug'53 upon the lever 33 and for moving the same in a clockwise direction.

, A suitable whistle Ilia or other sound producing means (Fig. 4) may be connected by means of a conduit 46a to the exhaust side of valve 33.

A suitable needle valve as in Fig. 1 may be provided for governingthe flow of pressure agent through conduit 43, whereby the speed oi piston 43 and thus the duration of the sound impulse is controlled.

It is desirable for a number of purposes to provide a switch,-operable by lever 33, whichmay be either opened or closed during the period 01 the sound impulse. Use can be made of such a switch, for example, to actuate means which will prevent a sound receiver of the sonic altimeter from receiving the sound impulse while it is being produced. A switch 54 is provided for the above purpose and is actuated by means of a lever The trigger 64 will still be disengaged from latch at 63 and yieldingly urged in a clockwise direction by a spring 31 attached above pivot 36. Below, said pivot lever 33 engages a sleeve 33 slidably mounted upon a rod- 33 which loosely extends at one extremity thereof through a shoulder 33 upon lever 33. Interposed between said shoulder and sleeve is a coil spring 3| which surrounds rod 33 and urges lever 33 in a counter-clockwise direction. when the lever 33 is in the cooked position as shown in Fig. 5, the springs 31 and 6| balance one another and the'switch is open. Compression of spring 3|, however, will destroy thisbal'ance, to pivot the lever 55 and operate the switch 64.

Novel means are provided for retaining lever 33 in a cocked position which are effective to engage and retain the lever immediately when it is returned after a previous release, even while 33, pivotally mounted the releasing means are energized. The means which is attached to an armature 66 of an elec- ,.tromagnet 61. Trigger 63 is yieldingly urged in a clockwise direction by means of a spring 63. Armature 66 is pivotally mounted at 66c and yieldingly urged also in a clockwise direction, 1. e., away from magnet 61, by a leaf spring 63.

In operation 01' this embodiment, electromagnet .61 is energized, armature 66 is attracted thereto and moves in a counterclockwise direction against the pressure. of leaf spring 63. Lever moves with said armature and lifts trigger portion 63 which is engaging latch 63 (Fig. 5). The lifting of said trigger will also lift'the latch 63 which becomes disengaged from the catch portion 62 and releases lever 33 which .is yieldingly drawn by spring 43 towards the valve rod 42. When lever 33 reaches the point where it opens valve 33 (Fig. 6), the catch portion 32 strikes and moves the pivotally mounted triger 64 in a counter-clockwise direction whereby the latch 63 becomes disengaged therefrom'and falls upon the upper smooth surface of the catch 62 but not in such a position that it will engage the same. With valve 33 open, the pressure agent flows from container 34 to sound the whistle Illa. Piston 33 is moved against the pressure of coil spring 5| and the'rod 43. strikes and moves lever 33 in a direction opposite toits first movement whereby valve 33 is closed. The duration of the signal is governed by the needle valve (not shown) which controls the flow oi pressure agent through conduit 33. If, at theinstant that lever 33 is returned to its initial position, the electromagnet 61 is still energized, the parts will be in the position shown in Fig. '1.

33. The latch, upon the return of lever 33, which lever carries the catch portion 62 thereon, will by'gravity fall into and engage said condition of magnet 61. Consequently, a repetition of the above-described events will not ocin turn, is pivotally mounted upon a lever 63 catch regardless of the energized or deenergizedimpulse may be accurately controlled. The device is not complicated,-and its manner of operation is simple. The apparatus is especially adapted for use with sonic altimeters for aircraft wherein it is necessary to produce sound impulses of very short duration at low altitudes and of longer duration at high altitudes. Not only is the speed at which the control valve moves controllable but the nature of its motion, i. e., uniform or intermittently slow and rapid, is also governable. The device is positive in operation, there being means for preventing undesired repetitions of sound impulses. and, furthermore, it requires only a small amount of space.

Although only two embodiments of the present invention have been illustrated and described in detail, it is to be expressly understood that the invention is not limited thereto. For example, in the embodiments shown, the valve opening lever is returned to its initial position by a piston rod which is actuated by a pressure medium acting upon a piston. However, suitable electrical return means which are energ ed by a pressure agent acting upon an electric switch may be employed instead. Various changes may also be made in the design and arrangement of parts without departing from the spirit and scope of the invention as the same will now be understood by those skilled in the art. For a deflnition of the limits of the invention, reference will be had primarily to the appended claims.

What is claimed is:

1. In a sound transmitter device for an aircraft sonic altimeter, fluid pressure operated sound producing means, a conduit in communication with said means for conducting fluid pressure thereto, a valve normally resiliently urged to a closed position in said conduit for preventing fluid pressure flow to said sound producing means, a valve rod mounting said valve for reciprocal movement within said conduit against said resilient action, actuating means including a hammer for engaging said valve rod to open said valve, means for releasably maintaining said actuating means in non-actuating position, whereby upon release of said actuatingmeans said hammer engages said valve rod to urge said valve to an open position causing fluid pressure to flow to said sound producing means, means for actuating said. last-named means to release said actuating means whereby said hammer engages said valve rod to open said valve, and means responsive to the fluid pressure in said conduit when said valve-is open for disabling said actuating means and disengaging said hammer from said valve rod whereby said valve resumes its closed position.

2. In a sound V craft sonic altimeter, sound producing means,

fluid pressure operated a conduit in communication-with said means for conducting fluid pressure thereto, a valve normally resiliently urged to a closed position in said conduit for preventing fluid pressure flow to said sound producing means, a valve rod mounting said valve for reciprocal movement within said conduit against said resilient action, actuating means including a hammer for engaging said valve rod to open said valve, means for releasably maintaining said actuating means in non-actuating position whereby upon release of said actuating means said hammer engages said valve rod to urgesaid valve to an open position causing fluid pressure to flow to said sound producing means,

transmitter device for an airing to said sound said maintaining means to release said actuating means whereby saidhammer engages said valve rod to open said valve, means responsive to the fluid pressure in said conduit when said valve is open for disabling said actuating means and disengaging said hammer from said valve rod whereby said valve resumes its closed position, and means associated with said last-named means for governing the speed of operation of said last-named means.

3. In a sound transmitter device for an aircraft sonic altimeter, fluid pressure operated sound producing means, a conduit in communication with said means for conducting fluid pressure thereto, a valve normally resiliently urged to a closed position in said conduit for preventing fluid pressure flow to said sound producing means, a valve rod mounting said valve for reciprocal movement within said conduit against said resilient action, a pivoted hammer for engaging said valve rod to open said valve whereby fluid pressure flows to said sound producing means, and means comprising a plunger subjected to the pressure of said fluid when said valve is open for disengaging said hammer from said valve rod whereby said valve resumes its closed position. I

4. In a sound transmitter device for an aircraft sonic altimeter, fluid pressure operated sound producing means, a conduit in communication with said means for conducting fluid pressure thereto, a control valve in said conduit normally resiliently urged to its closed position whereby fluid pressure is prevented from flowproducing means, a valve rod mounting said control valve for reciprocal movement within said conduit against said resilient action, a cylinder in communication with said conduit. 2. plunger in said cylinder, means for controlling the fluid pressure flow to .said cylinder, and pivoted hammer means for engaging said valve rod to open said valve, said plunger being movable as a function of the pressure in said conduit when said valve is open to engage said pivoted hammer means whereby said valve rod is disengaged and said valve resumes its closed position.

5. In a sound transmitter for an aircraft sonic altimeter. fluid pressure sound producing means, a conduit in communication with said means for conducting fluid pressure thereto, a valve normally resiliently urged to a closed position in said conduit for preventing fluid pressure flow to said sound producing means, a valve rod mounting said valve for reciprocal movement within said conduit against said resilient action, a pivoted lever including a hammer resiliently urged in one direction to engage said valve rod and open said valve whereby fluid pressure flows to said sound producing means, a latch for holding said lever and hammer in another direction whereby said valve rod is disengaged and said valve is closed, and means including a plunger responding to the fluid pressure in said conduit when said valve is open for en a ing and returnin said lever to its latched position.

6. In a soundtransmitter for an aircraft sonic altimeter, fluid pressure sound producing 'means, a conduit in communication with said means for means for actuating conducting fluid pressure thereto, a valve noroted lever resiliently urged to engage said valve rod so as to open said valve, a latch cooperating with said lever to lock the same, means for releasing said latch whereby said lever is resillently urged to a position to engage said valve rod to open said valve whereby fluid pressure flows to said sound producing means, a cylinder in communication with said conduit, a plunger in said cylinder, means for controlling the flow of fluid pressure to said cylinder, and means connected with said plunger for engaging and moving the lever to locked position whereby said valve rod is disengaged and said valve assumes its closed position.

' 7. In a sound transmitter device for an air.- craft sonic altimeter, fluid pressure sound producing means, a conduit in communication with said means for conducting fluid pressure thereto, a valve normally resiliently urged to a closed position in said conduit for preventing fluid pressure flow to said sound producing means, a valve rod mounting said valve for reciprocal movement within said conduit against said resilient action, actuating means including a hammer rcslliently urged to engage said valve rod to open said valve whereby fluid pressure flows to said sound producing means, a cylinder having two bores of difiering diameters, a piston in each of said bores, a piston rod mounting said pistons for movement in said cylinder, said cylinder being in communication with said conduit at a point between said pistons whereby fluid pressure flows to said cylinder when said valve is open to move said pistons whereby said piston rod engages said hammer, said valve moving to a closed position when said hammer is disengaged from said valve rod by said piston rod.

HELMUT REHM. l

HANS SCHUCHMANN. 

